A principal objective is to refine and complete the structure determination of alpha-chymotrypsin (alpha-CHT) dimer at 1.8A resolution. The structures of the two independent molecules in the asymmetric unit will be compared in detail to fix, correlate and catalog the structural differences between them. The nature and details of the asymmetry catalog the structural differences between them. The nature and details of the asymmetry will form the basis for describing and investigating other such oligomeric systems and will form the guiding and underlying principles for the description of the expression of functionality of the dimeric molecule. In the study of the latter, through interaction with a wide variety of small molecules, the behavior of classes of interaction and differences within a class will be elucidated. This will be accomplished using new representations of the difference electron density in diagonal distance format (DDP). The DDP's of different classes of functionality and of members within a class will be compared and correlated in order to surface generalities such as the nature of the asymmetry of responses to interaction with different small molecules and preferential sensitivities to structural changes of different folding domains. In the very least, these studies of structural changes and motions will form the basis and framework within which presently popular theoretical biomacromolecular mechanics and dynamics calculations will have to abide. Attempts will also be made to obtain the structures of longer-lived enzyme-substrate complexes at low temperatures (approximately 100 degrees C) and at 1.8A resolution to finalize discussions of catalysis.